1. Field of the Present Invention
The present invention relates to a power transmission for electric motor vehicles such as motorcycles and auto-tricycles having an electric motor as the source of power, and more particularly, to a power transmission device which employs a belt-driven non-shift transmission.
The present invention is also related to a regenerative braking device for electric motor vehicles, and more particularly, to a regenerative braking device which controls a duty factor of control signals which actuate a charging circuit to effectuate braking power without becoming excessive or losing driveability of the vehicle.
2. Conventional Art
Conventional electric motor vehicles are exemplarily described in the Japanese Patent Application Laid-Open No. 54-38043 which discloses an electric motor vehicle having a direct-current motor as a source of power and a clutch to engage with the motor when the motor is rotating to drive the vehicle.
Also, as described in the Japanese Patent Application Laid-Open No. 2-36701, a regenerative brake device employed for electric motor vehicles has an electric motor, a battery and a battery charging device with switch elements bridge-wired thereto. When braking is applied, the regenerative brake device outputs control pulse signals to the battery charging circuit to cause the battery charging circuit to switch OFF and ON, thereby charging the battery with power generated by the electric motor.
Since the characteristic structure of the electric motor vehicle causes the engagement and disengagement of the clutch device to be controlled simply by the rotational speed of the electric motors, the conventional electric motor vehicles, as discussed above, pose a problem such that the driveability of the vehicle is inevitably impaired when the motor, at the time when power transferred from the driving wheel to the electric motor is damped or decelerated, slows down and is disengaged from the driving wheel.
As is also conventionally known, an electric motor vehicle has mounted thereon an electric motor powered by a battery to drive and run the vehicle. It is common to employ electric braking by utilizing kinetic energy of the vehicle to charge the battery.
The electric braking is carried out by charging the battery through the electric motor. The charging of the battery is controlled by control signals having a certain duty factor. When the duty factor of the control pulse signals inputted to the battery charging circuit is constant, as described above, the braking power relative to the rotation of a motor inevitably demonstrates upwardly-projected parabolic characteristics as illustrated in FIG. 16. When these characteristics reach their maximum peak, braking power becomes excessive and causes impairment to the driveability of the vehicle during braking.
It may be recognized to solve the above-described problem by selecting a duty factor for the control pulse signals in a range to prevent the braking power from becoming excessive at the maximum. However, such an attempt may lead to yet another problem as it causes the braking power demonstrating upwardly-projected parabolic characteristics to become lower in the range of high-speed and low-speed rotation such that not enough braking power is available at the high-speed range.